Almost any surface can be susceptible to bacterial colonization. Bacteria can attach to surfaces either by non-specific mechanisms such as hydrophobic interactions or by specific mechanisms such as ligand-receptor interactions. As the bacteria grow and divide, they often surround themselves with a matrix that allows the influx of nutrients and that provides protection from agents harmful to their viability. The matrix (i.e., glycocalyx) includes polysaccharides as well as other substances such as proteins, minerals, and nucleic acids. The glycocalyx together with the included bacteria form a structure referred to as a biofilm. Many of the microorganisms in our environment exist as biofilms. Bacteria that exist in a biofilm are usually much more difficult to kill than planktonic, or free-living, bacteria. Much higher levels of an antimicrobial agent may be needed or the antimicrobial agent may need to be applied for a longer period of time to kill bacteria in a biofilm.
Surface contamination caused by disease causing bacteria in the home, workplace, or other public spaces can have significant human and economic impact. Bacterial biofilms can be involved in many diseases such as cystic fibrosis, Legionnaire's disease, dental caries, necrotizing fasciitis, and implanted medical device related infections. Nosocomial infections that affect both patients and medical staff in hospitals often require additional medical treatments that result in higher medical costs. In the food processing industry, contamination from fouled surfaces can cause food spoilage and pose a serious public health risk. In industry and civil services, biofilm growth in manufacturing equipment, piping, filters, and storage containers can result in ruined product and costly cleaning procedures. The fouling of marine vessels and other underwater surfaces may be initiated by the formation of a biofilm that attracts the organisms that populate these surfaces resulting in costly removal procedures.
Various biocidal materials are known. A biocidal material can be coated on a surface to provide an antimicrobial coating. In some instances, the biocidal material can be depleted from the coating over time through processes such as diffusion or extraction. In other instances, the biocidal material remains on the surface but the surface becomes contaminated with dead microbes or other insoluble contaminants.